1. Field of the Invention
The present invention relates generally to a dynamometer for testing performance of a vehicle, such as an automotive vehicle.
2. Description of the Background Art
In automotive industries, chassis dynamometers have been used for testing performance of automotive vehicles by simulating running resistance, up- and down-hill road, vehicular load and so forth. Such chassis dynamometers are conveniently used for a simulated road test in order to measure performance of the vehicle and/or to measure fuel consumption. For such chassis dynamometers, appropriately setting conditions of testing is a most important feature for determining accuracy level of the results.
For example, it is important for simulating inertia moment which is variable depending upon overall weight of the vehicle. For simulating inertia moment to be exerted on the vehicle during actual driving, a flywheel has been utilized. A typical construction of the chassis dynamometer has been disclosed in Japanese Patent First (unexamined) Publication (Tokkai) Showa 60-149944, published on Aug. 7, 1985. In the publication, there is disclosed a chassis dynamometer for which the flywheel is externally connected for simulating vehicular inertia weight.
In the recent years, there has been proposed a twin roller type chassis dynamometer which has provided two rollers. One of the rollers is designed to be placed at the vehicular tread to be rotatingly driven by the vehicular wheel, which roller is practically called a "free roller". The other wheel is coupled with the flywheel. In the further advanced technology, there has been developed and proposed the free roller, in which the flywheel is built in. As can be appreciated, for accurately simulating the vehicular inertia, it is essential to accurately adjust the inertia moment of the flywheel. The adjustment of the inertia moment on the flywheel can be done by adjusting the diameter of the flywheel since the inertia moment is proportional to the flywheel diameter. To this, difficulty is encountered in adjustment of the flywheel diameter due to limited space for building in the flywheel. Because of limited space to install the flywheel, it becomes necessary to use a heavier flywheel. In addition, since a relatively heavy flywheel is housed within the free roller, reinforcement for the free roller becomes essential to avoid the possibility of distortion, vibration and creation of noise.